Method of making heater support for pluralgun cathode-ray tube



Aprll 7, 1970 KRANER ET AL 3,504,412

METHOD OF MAKING HEATER SUPPORT FOR PLURAL GUN CATHODE-RAY TUBE Original Filed May 18, 1967 lnven1ors= Jo mes L. Kroner United States Patent US. Cl. 2925.16 4 Claims ABSTRACT OF THE DISCLOSURE A tri-color gun mount for a color television picture tube includes three rigid metal support straps each supported by and extending between two of the three parallel ceramic support rods, and two of the support straps are each provided with a depending integral car. A pair of fiat conductive strip connectors extend from the depending ears to the terminals of the heater element of one of the electron guns, and another pair of flat conductive connectors are respectively welded to the first pair and extend between corresponding terminals of the other two heater elements of the tri-color gun mount.

CROSS-REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 639,496, filed May 18, 1967, now Patent No. 3,387,166, for Heater Support for Plural Gun Cathode-Ray Tube, and assigned to the same assignee as the present application.

BACKGROUND OF THE INVENTION The present invention relates to plural beam cathoderay tubes of the type having separate thermionic cathodes and associated heaters for each of a plurality of electron guns. More specifically, the invention is directed to a new and improved method of manufacturing heater support assemblies for such cathode-ray tubes.

In a conventional tri-color television picture tube, three separate electron beams are simultaneously projected through an aperture mask or shadow mask toward a mosaic type of phosphor screen' where they impinge on corresponding ones of three elemental phosphor areas. The three beams originate from respectively different electron guns located in the tube neck, each of the guns being equally spaced from the geometrical axis of the tube in What may be considered a triangular or delta array. Each electron gun is provided with a thermionic cathode and an associated individual heater element. The heaters must be mechanically supported closely adjacent their respective cathodes and must be provided with a suitable electrical heating current.

conventionally, the tri-gun assembly is formed as a single mechanical unit. The electrode series of each gun is disposed on a respective one of three mandrels which are spaced in the desired delta configuration. Each of the electrodes is provided with a mounting strap and the stacked electrodes are rotated to align these straps after which three insulative support elements or glass pillars are heated to their softening temperature and then impaled on respective groupings of the support straps. The foregoing procedure has been found to be an efficient and precise method of assembling the gun complex, Unfortunately, however, the individual heater elements of the electron guns are not readily suited to a jigging operation and, therefore, it is quite difficult to precisely mount the heaters within their associated cathodes.

BRIEF DESCRIPTION OF THE INVENTION Accrodingly, the invention relates to a method of manufacturing a heater support assembly for a color cathoderay tube of the type having separate thermionic cathodes and associated heaters for each of a plurality of electron guns which guns are assembled in a predetermined array by means including a plurality of insulative support elements. The support assembly is made from a pair of thin metal stampings each comprising first and second elongated sections having terminal ends adapted to be received in the insulative support elements and being interconnected by a relatively narrow intermediate section. Specifically, the method of the invention contemplates fixing the first sections of the stampings to respective ones of the electron guns and fixing the terminal ends of the first and second sections of both of the stampings to predetermined ones of the insulative support elements. The intermediate sections of both of the stampings are then severed, preferably by applying a high electrical current therethrough.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the present invention which are believed to be novel are set forth with particularly in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in the several figures of which like reference numerals identify like elements, and in which:

FIGURE 1 is a perspective view, partly in section, of the neck portion of a plural beam cathode-ray tube containing an electron gun complex embodying the present invention;

FIGURE 2 is a cross-sectional view taken along line 22 of FIGURE 1;

FIGURE 3 is a cross-sectional view taken along line 33 of FIGURE 1; and

FIGURE 4 is a perspective view of a metal stamping used in making the support assembly of the invention.

FIGURE 1 illustrates the neck portion of a tri-color cathode-ray tube having three electron guns disposed therein to project separate electron beams to a mosaictype phosphor screen (not shown). It is to be understood that except for the invention to be described the entire color picture tube may be of any construction well-known to the art. The tube neck comprises a cylindrical glass envelope section 10 closed at its base by a glass press 12. As is conventional, a number of lead-in pins 14 are arranged about a central indexing post 16 and project into the envelope through press 12 to provide electrical connections for the various elements therein.

The three electron guns are identical in construction and are arranged in a delta or triangular configuration in the tube neck; only one of these guns 17 is visible in the drawing. Gun 17 comprises a cathode assembly comprising a tubular sleeve member 20 on the closed end of which is deposited a thermionically emissive coating 22 of barium oxide or the like. Cathode sleeve 20 is held with its emissive surface adjacent the central aperture of a first grid electrode 24 by a ceramic washer 26. Washer 26 is fixed within grid cylinder 24 by peripheral flange members located on opposite sides of the washer in conventional fashion. Gun 17 includes several other serially aligned electrodes of which only a screen grid or first anode 27 and a first focusing electrode 28 are shown in the drawing. These electrodes are held in a predetermined fixed spatial relation by individual mounting straps (not shown) having central sections spot-welded to the electrode and end portions embedded in predetermined ones of three glass support pillars. For clarity, only support strap 32 for grid control 24 is illustrated in the drawing, although it will be understood that the other gun electrodes are similarly mounted. The end portions of strap 32 are embedded in glass pillars 33, 34, as denoted by the dashed lines in the drawing, and have a conventional claw-like configuration to insure a good mechanical connection therewith.

A better view of the manner in which the grid electrodes are supported is provided in FIGURE 2. Before proceeding, it should be noted that in the ensuing description single and double primed reference numerals Will be employed to designate the corresponding elements of the other two electron guns not visible in FIGURE 1. Grid straps 32, 32' and 32" are spot-welded to corresponding control grid cylinders and each strap extends between an indicated pair of glass pillars 33, 34, and 3:, pillar 35 being not visible in FIGURE 1.

As previously stated, the individual cathodes of the three electron guns are of the thermionic type and for this reason an individual resistance heater element 37 (see FIGURE 1) is disposed within each cathode sleeve 20. Heater 37 is of a conventional coil construction and is located with its coils closely adjacent the end wall of sleeve 20 on which is deposited the emissive coating. The lower ends of coil 37 project from the open end of the cathode sleeve and are provided with respective flat terminal connectors 39 and 40.

In accordance with the invention, the several heaters are precisely yet ruggedly held in juxtaposition to an associated cathode by a support assembly comprising a pair of elongated conductive support members, only one of which members 41 is fully visible in FIGURE 1. Member 41 includes a depending integral ear portion 42 near one of its extremities and may optionally include a second such ear portion 43 at its opposite end to provide symmetry to the piece and obviate any indexing problems during construction. The depending ear portions 42 and 42' of members 41 and 41' can be seen in FIGURE 1 and it will be observed that the ears are formed to contact adjacent lead-in pins 14. Pre-forming of the support members in this manner facilitates construction of the gun complex.

Support member 41 and its companion support member 41' are both visible in FIGURE 3. As shown, both have one end affixed in pillar 33, while their opposite ends are afiixed in pillars 34 and 35, respectively. Also most clearly visible in FIGURE 3 are four flat, elongated conductive strips 46-49, each of which has its opposite end portions twisted to form respective predetermined angles (ninety degrees as shown) with its planar central portion. Strips 46 and 47 each have one end wrapped around a respective depending ear of support straps 41 and 41 and, of course, also welded thereto while their opposite ends are spot-welded to flat heater connecting terminals 39" and respectively. Conductive strips 48 and 49 are oriented transverse to strips 46 and 47 and have their opposite end portions spot-welded to corresponding terminals of heaters 37 and 37'. The central portions of strips 47, 49 and 46, 48 are likewise spot-welded to one another as indicated schematically in the drawing; the strip pairs that are welded together are axially spaced from each other, as seen in FIGURE 1, a sufiicient distance to avoid possible electrical shorts therebetween. The interconnection of the conductive strips in this manner effects a parallel electrical circuit connection to the several heaters from a pair of lead-in pins. The twists which are provided in all of the conductive strips assure a planar meeting of surfaces at all of the afi'ixation points to provide an optimum welding condition creating a mechanically rugged and dependable connection with a low electrical resistance between the elements.

In accordance with the method of the invention, the grid and heater support straps 32 and 41 are originally manufactured as a unitary structure. A perspective view of the in g al structure, which. is preferably formed by a conventional metal stamping process, is seen in FIG- URE 4. As shown, the assembly comprises first and second elongated sections 32 and 41, respectively, which are interconnected by a relatively narrow intermediate section 52; a second similar intermediate section 53, spaced from portion 52, is provided to give added strength to the interconnection without undue thickness. A pair of bands like that illustrated in FIGURE 4 are employed in the inventive construction. Specifically, the first sections of these bands 32 and 32, as shown in FIGURE 2, are affixed to respective first grid electrodes 24 and 24' by spot-welding at their mid-portion; the lower sections 41 and 41' are not physically attached to any electrode but, of course, are held in a fixed spatial relation to the grid electrodes by virtue of the intermediate connecting sections 52, '53.

All of the remaining electrodes of the several electron guns are provided with conventional support straps and, as previously stated, the electrodes are serially threaded in proper order over adjacent mandrels which are disposed to correspond with the desired spacing of the gun complex. The electrodes are oriented to properly align their support straps, and glass insulating pillars 33, 34 and 35 are forced onto the supporting straps after having been heated to their softening temperature. Upon cooling of the pillars, all of the electrodes of the three guns are permanently held in the selected orientation and relative spacing. Heater support sections 41 and 41' are likewise fixed in the pillars with a proper axial and rotational alignment by virtue of their interconnection to grid straps 32 and 32'.

Now that the intermediate connecting sections of the stampings have performed their locating function for the heater support members, the connections between the control grid straps and these members is severed. The severing is most simply done by applying a sufiicient electrical current through the narrow intermediate sections to cause them to be melted by resistance heating, although mechani cal severing to remove portions of the intermediate connecting strips may be employed if desired. Conductive strips 46 and 47 are spot-welded together and attached to the depending ear portions 42 and 42', and the heater terminals are welded to strips 46 and 47 as shown. The heater electrodes of the several electron guns are now very nrmly supported within their respective cathode elements, and they receive ultimate support from the same glass pillars which retain all of the gun electrodes.

While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

We claim:

1. A method of manufacturing a heater support assembly for a color cathode-ray tube of the type having separate thermionic cathodes and associated heaters for each of a plurality of electron guns which guns are assembled in a predetermined array by means including a plurality of insulative support elements, said method comprising the steps of:

forming a pair of similar and integral conductive support members each having first and second elongated sections interconnected by a relatively narrow intermediate section, the terminal ends of said elongated sections being adapted to be received by said insulative support elements;

fixing said first section of each of said conductive members to a respective one of said electron guns;

fixing each end portion of said first and second sections of both of said conductive members to predetermined ones of said insulative support elements;

connecting said heaters to said second sections of said conductive members to both physically support said heaters and pro ide e ectrical co nections thereto;

and severing said intermediate sections of both of said conductive members.

2. The method according to claim 1 in which said intermediate sections are severed by applying an electrical current through said conductive members.

3. A method of manufacturing, for a color cathode-ray tube of the type having separate thermionic cathodes and associated heaters for each of aplurality of electron guns which guns are assembled in a predetermined array by means including a plurality of insulative support elements, a heater support assembly from a pair of thin metal stampings each comprising first and second elongated sections having terminal ends adapted to be received in said insulative support elements and being interconnected by a relatively narrow intermediate section, said method comprising the steps of:

fixing said first sections of said stampings to respective ones of said electron guns;

fixing said terminal ends of said first and second sections of both of said stampings to predetermined ones of said insulative support elements;

References Cited UNITED STATES PATENTS 3,134,923 5/1964 Brown.

3,238,409 3/ 1966 Brown.

3,322,990 5/1967 Fiore.

3,353,049 11/1967 Pappadis.

3,391,298 7/1968 Dorota 313- 271 3,396,298 8/1968 Kuryla.

JOHN F. CAMPBELL, Primary Examiner 20 V. A. D. PALMA, Assistant Examiner 

